SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f1a8f838e8a9ca522499e420a14e829ac6280976de1bff64d31cb118184eb8' 
  AND token = 'YGPYhxE+iq4mW2L4QBMqGqMc6GzAC+hvt6NSBtMl2PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}